A conventional surface mounting apparatus of this type is disclosed, for example, in Japanese Patent No. 3227881.
The surface mounting apparatus is equipped with a board transfer device that transports a printed wiring board by pushing the printed wiring board using tab members. The board transfer device transports a printed wiring board from a loading unit to a mounting unit. The board transfer device is provided with the tab members located at positions to pinch a printed wiring board from upstream and downstream in the transportation direction.
These tab members include a rear tab member located upstream of a printed wiring board in the transportation direction and a front tab member located downstream in the transportation direction, and both are attached to a single movable arm so as to hang down from above. The movable arm reciprocates both in the transportation direction of a printed wiring board and in the top-bottom direction at predetermined timings and moves in a movement path that draws a rectangular shape when viewed from the side.
While the movable arm moves as described above, the rear tab member and the front tab member descend to transportation positions at which the lower ends are located below a printed wiring board first, and thence move downstream in the transportation direction, after which they ascend to positions higher than the printed wiring board and moves further upstream in the transportation direction until they return to the initial positions.
The rear tab member is provided with a sensor to measure the length of a printed wiring board. The sensor passes above a printed wiring board placed on the loading unit when the tab members are returning to the initial positions after the printed wiring board is transported using the tab members. The printed wiring board on the loading unit is held at a predetermined position as the edge on the downstream side in the transportation direction abuts on a stopper provided to the loading unit.
The board transfer device adopts a configuration in which the length of a printed wiring board in the transportation direction is measured using the sensor that moves above the printed wiring board as described above and then the position of the edge of the printed wiring board on the upstream side in the transportation direction and a transportation stroke during transportation are found through computation.
In order to transport a printed wiring board using the board transfer device configured as above, the rear tab member and the front tab member located above the loading unit are lowered so that they are respectively located at transportation positions upstream and downstream of the printed wiring board in the transportation direction and the movable arm is moved in the transportation direction in this state. According to the board transfer device, a single printed wiring board is transported from the loading position to the mounting position.
Meanwhile, a conventional surface mounting apparatus as the one shown in Japanese Patent No. 3227881 above is used in some cases to mount remaining electronic components on a printed wiring board on which a part of the electronic components have been mounted by another surface mounting apparatus in a preceding process.